The present invention relates to a speech recognition system which is suitable for the use in a car navigation system, a small-size information equipment represented by PDA (Personal Digital Assistant), a portable speech translator or the like, and more particularly to a speech recognition guidance system which is suitable for the use in the car navigation system for the speech recognition of enormous words including the names of places, intersections, roads, and so forth.
In recent years, small-size information systems using speech recognition techniques are being popularized. Such a system includes a portable information equipment represented by PDA, a portable translator and so forth, inclusive of a car navigation system. In the small-size information system of the prior art, however, the number of words to be recognized is restricted in order that the rate of recognition and a recognition response time performance are not deteriorated.
Also, JP-A-5-35776 entitled "TRANSLATION APPARATUS WITH AUTOMATIC LANGUAGE SELECTING FUNCTION" has disclosed a portable translation apparatus which recognizes an operator's speech inputted from a microphone for translation it and outputs a speech in a translated language.
FIG. 8 is a block diagram showing an example of such a conventional speech translation apparatus. In FIG. 8, reference numeral 801 denotes a control section, numeral 802 a speech section extraction section, numeral 803 a speech recognition section, numeral 804 a display section, numeral 805 a speech synthesis section, numeral 806 an equivalent data memory card, numeral 807 a speech recognition dictionary section, numeral 808 a speaker, numeral 809 a microphone, numeral 810 a speaker amplifier, and numeral 811 an operating signal.
The control section 801 includes a micro-computer or the like and controls each section of the apparatus. The speech section extraction section 802 extracts a speech input from the microphone 809. The extraction is made in a form converted into a digital signal. The extracted speech is sent to the speech recognition section 803. In accordance with an instruction from the control section 801 receiving the operating signal 811 derived from a keyboard, switch or the like, the speech recognition section 803 analyzes the speech input from the microphone 809 and extracted through the speech section extraction section 802. The speech recognition section 803 performs speech recognition by comparing the result of analysis with standard speech patterns stored in the speech recognition dictionary section 807.
The speech synthesis section 805 reads data information equivalent to the recognized speech from the equivalent data memory card 806 and converts the information equivalent into an aural signal which is in turn output as a speech through the speaker amplifier 810 and the speaker 808.
The display section 804 provides an indication to a user of the translation apparatus or a visual display of the equivalent by characters. The equivalent data memory card 806 includes a read-only-memory ROM or the like. In the case where the data information equivalent is output in a speech synthesized form, speech data is stored in the equivalent data memory card 806. Also, a character code corresponding to the data information equivalent is read from the equivalent data memory card 806 so that it is displayed on the display section 804. The exchange of the equivalent data memory card 806 for a memory card of another language makes the translation into a plurality of languages possible. The speech recognition dictionary section 807 includes a data-access-memory RAM or the like. Standard speech patterns corresponding to the speech of the operator are stored in the speech recognition dictionary section 807. The standard speech patterns are stored by the operator beforehand.